Refrigeration



March 3, 1942. c. H. M FARLAND 2,274,956

REFRIGERATION,

Fild Jan. 13, 1958 s Sheets-Sheet 1 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII 1 745 I "-I-In--n-nn-u-u-n-n-nu r v myzm'on 'lzarfea h: wry

March 3,1942. c. H, MaCFARLAND 2,274,966

REFRIGERAT ION Filed Jan. 13, 1938 3 Sheets-Sheet 2 mvsu'ron Char/; 15. Mac

Far/and M/py ATTORNIY Mancini 3,1942; c, H, MaCFARLAND 2,274,966

REFRIGERATION Filed Jan. 1:5, 1938 s Sheets-Sheet 3 INVENTOR filzarle H Mac fZzr/and ATTORNEY Patented Mar. 3, 1 942 UNITED STATES PATIENT OFFICE.

REFR GERATION CharlesH. MacFarland, North Canton, Ohio, as-

signor to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application January 1a, 1938, Serial No. 184,746

28 Claims.

This invention relates to control mechanisms and more particularly to control mechanism particularly designed for use with refrigerating systems of the absorption type.

I-Ieretofore, control mechanisms designed for refrigerating systems having a source of heat and a source of electrical energy to be controlled have provided separate control elements for the source of heat and the source of electrical energy. These elements must be synchronized and remain in proper synchronism throughout the entire range of adjustment thereof and during the defrosting period. Not only is initial adjustment and synchronization difiicult but there are many possibilities for loss of adjustment of any or all the various control elements. Furthermore, separate safety controls and manual shutoff mechanisms must be provided.

According to the present invention there is provided a control mechanism particularly designed to control the operation of an electrical motor and a gas burner and so arranged that only a single control mechanism is required. The magnetic field of the motor is utilized to control the valve supplying gas to the gas burner whereby it is only necessary to control the supply of electrical energy to the circulating motor in order completely to control the entire machine. More specifically, a single switch element is operative to control both the gas valve and the electrical motor and perfect synchronism between the two is assured. Also, a defrosting device is provided which operates upon the switch normally controlling the gas valve and electrical motor but without in any way disturbing the calibration thereof or its particular adjusted setting.

I'here is provided a novel form of flame failure safety cut-off device which operates upon the normal control contact to de-energize both the electric motor and the gas burner upon flame failure and all this without in any way disturbing the calibration or adjustment of the normal control device or the defrosting control. Moreover, the safety cut-oil device operates a simple visual signal means to indicate to the operator of the refrigerating system whether or not an igniting flame is present at the gas burner.

The control is so arranged that the system is automatically shut down upon failure of fuel' and/or electrical energy. The safety shut down n'i'echanism protects against any dangerous con dition which might arise from failure of fuel or electrical energy but without the addition of complex controls and without affecting the adjustment of the normal control mechanism.

In addition to the normal control and the defrosting cut-ofl, a manual cut-oil! may be provided which operates upon the same mechanism but without disturbing the adjustment thereof in order that the housewife may entirely de-energize the system without disturbing any electrical or gas connections.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic representation of a continuous three-fluid absorption refrigerating system which I have elected in order to illustrate my invention.

Figure 2 is an isometric schematic diagram of the control mechanism and its connections to the electrical motor and the gas burner.

Figure 3 is a plan view of a detail of the motor.

Figure 4 is a schematic isometric view of a.

modified form of control mechanism.

Figure 5 is a view partly in section of a detail of Figure 4.

Referring now to the drawings in detail and first to Figure 1 thereof, there is disclosed a continuous three-fluid absorption refrigerating system comprising a boiler B, an analyzer D, a condenser C, an evaporator E, an absorber A, and a circulating fan F driven by an electrical motor M suitably connected by various conduits to form a plurality of gas and liquid circuits.

It will be understood that the system just described is diagrammatic only and that my invention is equally well applicable to other types of refrigerating systems. For example, my invention may be applied to a two-fluid absorption system utilizing an electrical motor-driven pump in the absorption solution circuit or to a continuous three-fluid absorption system of the type utilizing density differentials to produce circulation of the inert gas and a motor-driven fan to cool the absorber and the condenser.

The refrigerating system just described is suitably charged with a refrigerant such as ammonia, an absorbent such as water, and an inert pressure equalizing medium, preferably a dense gas like nitrogen.

The boiler B normally contains a solution of refrigerant in an absorbent which liberates re-- frigerant vapor when heated. The refrigerant vapor passes upwardly through the analyzer D in counterfiow to strong absorption solution supplied thereto from a source to be described herethe absorber.

densetlon serves to generate further refrigerant vapor. The refrigerant vapor is conducted from the analyzer to the condenser through c, conduit M which includes an sir-cooled rectifier it. Any vapor of absorption solutioh which may escape from the analyzer is condensed in the rectifier it and returned to the analyzer.

The week solution formed in the boiler by the generation of reirigereht vapor is conducted therefrom through a. conduit 92, liquid heat ex changer it, and conduit into the upper end of the sir-cooled absorber A. Week solution flows downwardly through the absorber h in counter-- flow to rich pressure equalizing medium coming from the evaporator so will be described more fully hereiheiter. The refrigerant vapor content of the pressure equelizihg medium stream is ebsorbed by the solution in the absorber to form strong solution which collects in the bottom of The strong solution is conveyed ircm the absorber to the upper portion of the analyzer D through a conduit iii, liquid heat exchanger l3, and e. conduit i6. It is apparent the r, the upper end of the absorber A is at an elevation substantially higher than the liquid level normally prevailing in the boiler-analyzer system wherefor it is necessary that some means he provided to elevate the week solution, into the absorber. For this purpose, a bleed-oil conduit ill is connected between the discharge conduit iii of the circulating fan F and the conduit ill below the liquid level normally prevailing in the boiler-analyzer system whereby the solution is elevated into the absorber by gas lift action.

The lean pressure equalizingmedium formed in the absorber exits from the upper end thereof through a conduit it into the suction inlet of the circulating fan F. The gas is placed under pressure in the fan F and is discharged through the conduit l8 into a, gas heat exchanger 20. The lean pressure equalizing medi um is discharged from the heat exchanger 2b through a conduit 2| which opens into the lower portion of the evaporator E. The evaporator E may be of any desired construction. It is shown diagrammatically herein. Preferably the evaporator will include box-cooling and freezing sections. The pressure equalizing medium flows upwardly through the evaporator E in. counterfiow relationship to liquid refrigerant which is supplied to the upper endthereof through a. conduit 22 communicating with the bottom portion of the air-cooled condenser C. The refrigerant evaporates into the pressure equalizing medium to produce refrigeration and theresulting rich gas is returned to the gas heat exchanger through a conduit 23. The righ gas is conducted from the heat exchanger 29 into the bottom portion of the absorber A through a conduit i l and passes upwardly therethrough in counterflow relationship to the absorption solution in a manner previously described.

The refrigerating system just described :is die.- grammatically illustrated and is selected for purposes of illustration only, my invention not being limited thereto but being equally well applicable to other types of refrigerating systems.

The first form of control mechanism will now be described with reference to Figures 1 to 3. The boiler B is heated by any suitable form, of gas burner 3!. fuel from a source of supply 32, a valve 33 which is mounted within the field structure of the motor M and'a conduit to. A suitable by pass conduit 35 is provided around the valve 83 in The gas burner is supplied with 'gas to flow to the burner 3!.

success order to provide a smell igniting home on the burner iii; however, a separate pilot burner may be connected to the line 35, if desired. The com duit'iit is extended though openings 36 formed incurs 3? which project outwardly irom one side of the held lcminctions of the motor field it smell plunger is of magnetic metterlel is mounted within the pipe 82 above a smell orifice M which is placed within the pipe The orifice is positioned below that portion of this pipe which is within the field or the motor whereby upon energizstion of the motor field, the magnetic field thereof will ele= veto the pin it shove the orifice ill and permit ges to how through the orifice to the burner iii. From this it will be seen that control or" the eriereizetioh oi the motor field simultaneously controls the circulation or". the inert gas through the evaporator end the absorber and the supply or heat to the boiler B. Y

The evaporator E is preferably housed within 2, casing 32, though if desired, a box-cooling section of the evaporator may be positioned outside the confines of the casing. A control panel 33 rises above the front portion of the evaporator casing and forms the front wall of 2. control box fil l.

Electrical energy is supplied to the apparatus through the wires 35 and 363. The wire 35 passes into the control box 66 end is connected to a bimetallic thermostatic switch contact elementit which is suitably mounted upon, 'and'insul ted from, the control box 65. A' complementary contact element 48 is mounted upon the front wallet of the casing 46 and is connected by means of a. wire 49 to one terminal of the motor field 39. The other terminal ofthe motor field is connected by the'wire 5E9 to the other supply line es.

The bimetallic thermostat ill is "designed" to be responsive to either box temperatures or evaporator temperatures, as mey bedesired; e rise in temperature causes the bimetallic-element 47 to flex downwardly, as viewed in Figure 2, to close the circuit through the contact t3 and to energize the motor field 39;; Energization of the motor field 39 places the circulsting motor in operation and also raises the pin fill to allow In order to adjust the temperature range of the refrigerating mechanism, an adjusting cam 5! is ca-rriedupon a. shaft 52 which is mounted in any 'suiteble manner on the control panel 63 and carries at its outer portion a. control dial 53. The control dial 53 is arranged to cooperate with suitable in dicis. 5% whereby theoperator. may set the re frigerating apparatus at any desired control point. The contact 48 is constructedof spring material and riormelly presses downwardly against the cam; the cam adjusts the vertical position of the contact 68 against the tension thereof and thereby the width of the space be= tween the contacts 41 and 48. This a.djust-' There is also provided a defrosting mechanism which comprises an insulating block '55 mounted on one endof an arm 55 which is pivotclly mounted at 56' on an arm 51. '-A torsion spring 58 urges the insulating block element-55 in a counter-clockwise direction as viewed in Figure 2. The element 55 cannot rotate beyond the engagement between the contacts 41 and porting arm 51. The arm 51 is pivotally mounted at 60 in a bracket 6I which is suitably carried by the front wall 43 of the control box. A defrosting knob 62 is carried by a shaft 63 which extends through a suitable opening in the control panel 43. Interiorly of the control box 44, the shaft 43, is provided with a slot 64 which receives the free end of the arm 51. The end of the shaft 63 carries a collar element 65 which receives the actuating arm 66 of a toggle mechanism 61. The toggle mechanism is arranged to urge the arm 63 to the position shown or, when the knob 62 is pushed inwardly to urge the end of the shaft 63 into contact with a defrosting bimetallic thermostat 68. When the knob 62 is pushed inwardiy for defrosting purposes, the arm 51 swings in a clockwise direction about the pivot 60, as

viewed in Figure 2, and f rces the insulating block 55 between the contacts 41 and 48 thereby preventing energization of the motor. M regardless of the setting of the dial 53. and the position of the bimetallic thermostat 41. When the evaporator has reachedv the defrosting temperature, the bimetallic thermostat 68 bends forwardly, as viewed in Figure 2, and snaps the mechanism 61 over center into the position shown, thereby withdrawing the block 55 from 48 whereupon the apparatus returns to normal operation; 1 I

In the position shown in Figure 2, the insulating block 55 abuts the free end of a bimetallic thermostat 69 suitably carried by the sidewall of the casing 44. Contactbetween the elements 65 and 80 determines the forward limit of the knob 62 under the bias of the snap mechanism 61. The bimetallic thermostat 63 carries a heating winding 10 which is connected by a wire H to the electrical supply wire .45 and by a wire 12 to the bulb 13:of a flame failure safety cut-off mechanism. The safety cut-off mechanism comprises the elongated bulb 13 which is carried by a bracket 14 in position to project the lower end thereof into the flame of the burner- 3I. The bulb 13 is an electrical conductor-andthe wire 12 extending downwardly thereinto is provided with insulation 15 except at the very bottom portion thereof which extends closely adjacent the bottom of the bulb 13. A small globule of mercury is placed within the bulb 13 to provide an electrical connection between the free end of the wire 12 and the vessel 13 except when the flame of the burner has vaporized the mercury whereupon the contact between the elements 12 and 13 is broken. Preferably the volume of the bulb 13 is very great with respect to the volume of the mercury globule and. the tube is highly evacuated before sealing. These features insure rapid and complete vaporization of the mercury in response to the pilot flame. radiating area of the bulb 13 renders the response of the cut-oil device to flame failure almost instantaneous as the heat of condensation of the tiny globule of mercury is very small and is dissipated from a very great area. The bulb 13 is connected by a wire 16 to the supply wire 46.

The pilot by-pass conduit 35 is provided with a valve IOI which is normally urged to closed position by a spring I02. A solenoid I03 is connected to open the valve against the bias of the spring I02. A ring I04 is provided in order that the valve I01 may be opened manually for igni- I03 is connected to the wire by a wire I05. The other side of the solenoid is connected to one contact of a switch I01 by a wire I08. The other contact of the switch I01 is connected to the wire 45 by a wire I09. The contacts of the switch I01 are of resilient material and are biased to open circuit position. An actuating block IIO of insulating material is mounted upon the bimetallic thermostat 69 in position to close the circuit between the contacts oi the switch I01 when the thermostat is in the position shown in Figure 2.

Whenever the flame of the burner 3| is completely extinguished for any reason, the mercury contained within the tube 13 condenses and closes the circuit to the wire 1i, coil 10, wire 12, bulb 13, wire 16 and line 46 whereby the thermostat 69 is heated. Heating of the thermostat 68 causes it to flex forwardly, as viewed in Figure 2, and to force the insulating block between the contacts" and 48 and to permit the contacts of the spring I01 to separate and to de-energize the normally energized solenoid I03. The insulating block 55 does not cause the entire shaft the bell crank carries a signal plate 80 which is positioneddirectly behind an opening 80a formed in the control panel 43. The signal plate 80 contains suitable indicia to indicate whether or not there is a flame carried by the burner 3I. The

other arm of the bell crank 11 rests against the bimetallic thermostat 69. The thermostat 69 pivots the bell crank 11 as it flexes to cause the plate 80 to indicate whether or not the gas burner is operating. I

The control mechanism just described operates automatically to cycle the refrigerating at will by suitable adjustment of the controldial 53. Furthermore, the circuit breaking ele- The large heat ment 55 is operable by either or both the defrosting mechanism and the safety cut-oil thermostat 69 as conditions may require. Defrosting may beaccompiished at any time simply by pushing inwardly on the dial 62 without in any manner affecting the setting of the normal control dial 53.

A modification of the invention is illustrated in Figures 4 and 5. This control mechanism is designed to control a refrigerating system similar to the mechanism disclosed in Figures 1 to 3. A number of elements of this control mechanism are identical with those described in connection with Figures 1 to 3 and are given the same reference characters primed. The thermostatic contact element 48' is connected by means of a wire 8| to a contact element 82 which is formed with a depression adapted to receive a ball-headed spring pressed contact element 33. The contact element 33 is carried on the end of a plunger 30 which is received within a collar 8! of insulating material which is mounted by means of a suitable bracket 92 from the front wall .of the casing 44'. A spring 83 is received tion of the burner 3I. One side of the solenoid 76 within the collar 8| between the plunger 80 and a bolt 94 so as to urge the contact 83 into engagement with the cam plate 85. The element 83 is connected by wire 84 to the field 39 of the motor M.

The contact element 82 is mounted within a plate member 85 which is carried by a shaft 86 suitably mounted in the wall 43' and carrying a dial 81 on the free end thereof. In addition to the depression in the contact 82, the plate 85 is provided with a defrosting depression 88 and a'shut-off depression 89; The plate 85 carries 9. depending pin 95 which is positioned withmember 91 corresponding to the element 55 is now mounted directly upon the safety cut-01f thermostat 89'. and is positioned to be projected between the contacts 41 and 88' in order to de-energize the system completely upon flame failure.

The plate member 85 is made of insulating material, therefore the circuit supplying energy to the field coils 39' of .the motor M is interrupted whenever the contact element 83 is seated in the depressions 88 or 89. When the dial 81 is turned to the defrosting position, the contact 83 seats in the depression 88 and the pin 95 is in the path.

of movement of the thermostat 98. Therefore, when the evaporator reaches a defrosting temperature, the thermostat 98 flexes in a counterclockwise direction, as viewed in Figure 4, against the pin 95 and rotates the plate 85 to the on position; that is, the contact 83 is now engaged .with the contact 82 and the system returns to normal operation at the end of the defrostin period. When the dial 8'! is turned to the position marked off on the control panel 43, the contact 83 is in the depression 89 and the pin 95 is rotated out of the path of movement of the thermostat 98 whereby the system is completely tie-energized and cannot be re-energizeduntil the dial 87 is moved to the "on position. This provides a convenient means for -de-energizing I the system, for example, during a vacation period,

without interfering with any of the electrical or gas connections, and for defrosting the system if for any reason it is not desired ,to use the semiautomatic defrosting device previously described.

The control mechanisms just described provide simple and compact structures which simultaneously regulate the supply of fuel to a ,gas burner and the supply of electrical energy to a circulating motor. The control mechanism is provided with a single thermostat which is readily adjustable to provide any desired temperatur gradient within the refrigerating cabinet. Due to the fact that the supply of gas to the burner is regulated by a valve energized from the magnetic field of the circulating motor, perfect synchronization between the operation of the circulating motor and the boiler heater is assured and only one thermal control device need be provided for regulating the action of both these elements. Furthermore, there is provided a defrosting mechanism which will provide for a defrosting cycle of the evaporator whenever desired but without in any way afampen fecting the adjustment of the normal control mechanism. The safety control mechanism will function positively to'de-energize the circulating motor and to shut off all supply of 'fuel to the burner upon failure of the electrical or fuel supplies orboth of them.

The unique safety cut-offdevice is certain in operation because of the fact that it is normally open-circuited by the vaporization of an element by the gas burner, condensation of the volatile element and energization of the cut-0d devices occurs immediately the flame fails. This mecha-' nism is highly advantageous not only because of its simplicity and certainty of action but also because of the fact that there are no moving parts to get out of order, to stick, or to require precise adjustment; the characteristic of the cut-0d device per se is fixed solely by the boiling tempera ture of the vaporizable electrical conductor bridging the contacts which govern the energization of the safety system.

While only two embodiments of the invention have been illustrated and described, -.it is not limited thereto but other variations and constructional forms may be used without departing from the spirit of the invention or the scope of the appended claims. a

I claim:

1. Absorption refrigerating apparatus comprising a pressure equalizing medium circuit burner, said valve being arranged to be controlled by said motor, means responsive to evaporator temperature conditions for controlling the energization of said motor, manually set means for de-energizing said motor, and means responsive to a defrosted condition of said, evaporator for rendering said manually set means inoperative.

2. That improvement in the art of refrigeration which includes the stepsof applying. heat to a solution to expel refrigerantvapor, liquefying thevapor, evaporating the liquid to produce refrigeration, absorbing the vapor in solution, propelling vapor into contact with the solution under the impulse of a magnetically produced force, regulating the rate of heat supply in accordance with the intensity of the magnetically producingpropelling force and regulating the intensity of the magnetically produced propelling force in accord with the demand for refrigeration.

3. That method of regulating absorption refrigerating systems of the type having a burner arranged to apply heat to a generator'to produce refrigerant and an electrical motor to circulate fluids within the system which includes the steps of regulating the supply of fuel to the burner by the magnetic field of the motor and controlling the energization of said magnetic field in response to demands for refrigeration.

@Absorption refrigerating apparatus including a generator, an evaporator, heating means for said generator, power-driven means for circulating a pressure equalizing medium through said evaporator, fuel supply means for said heating means, a valve in said fuel supply means positioned to be opened by the magnetic field of said motor, and means responsive to demands for re frigeration for controlling the energization of said magnetic field.

5. Absorption refrigerating apparatus including a generator, an evaporator, heating means for said generator, power-driven means for circulating a pressure equalizing medium through said evaporator, fuel supply means for said heat-. ing means, a valve in said fuel supply means positioned to be opened by the magnetic field of said motor, means responsive to demands for refrigeration .for controlling the energization of said magnetic field, means for adjusting the temperature setting of said last mentioned means, manually set defrosting means for rendering said temperature responsive means inoperative, and means responsive to a defrosting condition of said evaporator for rendering said defrosting means inoperative.

6. Refrigerating apparatus comprising an evaporator, a boiler, a gas burner for heating the boiler, an electric motor-driven fan for circulating fluid through said evaporator, a valve operated by the magnetic field of said motor for controlling said burner, means independent of said valve for supplying gas to maintain an igniting flame at said burner, a solenoid valve controlling said igniting flame supply means, a thermostatic switch for controlling the energization ofsaid motor in response to refrigeration demand, means for de-energizing said motor for defrosting purposes, means for re-energizing said motor when said evaporator has defrosted, a bulb positioned to be heated by the igniting flame at said burner, an electrical conductor in said bulb which will be vaporized by flame at said burner, electrical connections to said bulb arranged to be open circuited when said electrical conductor is vaporized, and means energized by said electrical conductor in response to flame failure at said burner for de-energizing said solenoid valve and for opening said thermostatic switch to de-energize said motor independently of the position of said switch and said defrosting means.

7. Refrigerating apparatus including a heating gas burner, an electrically energized fluid circulator, means responsive to refrigeration demand for controlling the 'energization of said circulator,

said body between said contacts and thermostatic means for withdrawing said body from said contacts, a flame failure responsive means, an ignition flame control switch, and means energized by said flame failure responsive means for open- .ing said ignition flame control switch andfor means actuated by said circulator for controlling the fuel supply to said burner, means providing an igniting flame at said burner, and means operative to de-energize said circulator upon failure of fuel supply to said burner, or failure of said igniting flame.

8. Refrigerating control mechanism comprising a temperature responsive switch mechanism, means for. varying the temperature at which said switch is operated, defrosting mechanism for rendering said switchineflective, and flame failure responsive mechanism for opening said switch independently of said defrosting mechanism and the operating temperatures thereof.

9. Control mechanism comprising a thermostatically operated switch, means for regulating the operating characteristics of said switch, a three position switch connected in series with said first mentioned switch, said threeposition switch having a closed circuit position and two open circuit positions, a defrosting thermostat for returning said switch to closed circuit position from one open circuit position, a flame failure responmoving said body between said contacts independently of said regulating means and said defrosting mechanism.

11. Refrigerating control mechanism comprising a thermostatic control device, a manually set control device, said manually set control device being settable in a plurality of positions in which said thermostatic control device is rendered ineffective to perform its normal functions and another position in which said thermostatic control device is unaffected thereby, and means responsive to an abnormal temperature condition for shifting said manually set control device from one of said plurality of positions to another Position.

12. Refrigerator control mechanism comprising a. pair of switch contacts, means urging one of said contacts to open circuit position, manually set means for adjusting the position of said contact which is urged to open position, temperature responsive means for actuating the other of said contacts to open and closed circuit positions, circuit interrupting means adapted to be placed between said contacts, and means for moving said circuit interrupting means to and from position between said contacts.

13. Refrigerator control mechanism comprising a pair of switchcontacts, means urging one of said contacts to open circuit position, manually set means for adjusting the position of said contact which is urged to open position, temperature responsive means for actuating the other of said contacts to open and closed circuit positions, circuit interrupting means adapted to be inserted between said contacts, manually set means for tact which is urged to open position, temperature responsive means for actuating the other of said contacts to open and closed circuit positions, manually set means for interrupting the fiow of electrical energy through said contacts in a plu rality of positions and for permitting such energy flow in another position, and temperature responsive means for returning said manually set means from one of said plurality of positions sive means, a pilot flame control switch, and

means energized by said flame failure responsive means for opening said pilot flame and thermostatically operated switches independently of to said another position.

15. In combination, a gas burner, an electric motor, said motor having a field piece provided with an opening therethrough, a magnetic valve element in said opening, means including said opening for supplying gas tosaid burner, temperature responsive means for controlling the energization of said motor, means for providing a pilot flame at said burner independently of said pilot flame fuel supply means.

said valve, a bulb positioned to be heated by said pilot flame, a body of mercury in said bulb, means forming an electric circuit including said body of mercury, means for de-energizing said motor and for discontinuing the supply of fuel to said pilot burner, said last mentioned means being energized by said electric circuit, the arrangement being such that said pilot flame vapo'rizes said mercury and opens said electric circuit.

16. A flame responsive device comprising a sealed evacuated vessel constructed from electrical conducting material, a body of mercury in said vessel, an electrical conductor having a portion thereof in said mercury and insulated from said vessel, and another electrical connection to said vessel whereby vaporization of the mercury breaks the electrical conducting path between said electrical conductor and said vessel.

17. In combination with an absorption refrigerating system of the type including an inert gas circuit, a motor driven inert gas circulator, a fuel burner for applying heat to a suitable portion of the system, means providing a fuel supply for a pilot flame for said burner, means actuated -by the magnetic field of said motor for governing the supply of fuel to said burner, refrigeration demand responsive means for regulating the energization of said motor, and flame failure responsive means for de-energizing said motor and 18. In combination with an absorption refrigerating system of the type including an inert gas circuit, a motor driven inert gas circulator, a fuel burner for applying heat to a suitable portion of the system, means actuated by the magnetic field ofsaid motor for governing the supply of fuel to said burner, refrigeration demand responsive means for regulating the energization of said motor, manually operable means for de-energizing said motor, anda defrosting release thermostat'for operating said manually operable means to a position in which said motor is energized.

' 20. In combination with an absorption refrigcrating. system of the type including an inert gas circuit, a motor driven inert gas circulator, a fuel burner for applying heat to a suitable portion of the system, means actuated by the magnetic field of said motor for governing the supply of fuel to said burner, refrigeration demand responsive means for regulating the energization of said motor, manually operable means movable to a plurality of positions in which said motor is deenergized, and a defrosting release thermostat operable to move said manually operable means from one one of said plurality of positions to another position in which said motor is energized.

21; Control mechanism for a fuel burner comprising a main fuel supply control means, a pilot flame fuel supply control means, a temperature control thermostat, and a safety cut-off device positioned in .heat transfer relationship with said burner-comprising an element adapted to change phase in response to the establishing or'extinguishing of flame adjacent said burner to open or close an electrical circuit, and an electrical circuit including all of said elements and arranged to operate on said fuel supply means to discontinue all fuel supply in response to failure of flame at said burner.

22. Absorption refrigerating apparatus including a motor driven fluid circulator, a fuel burner, means actuated by said motor for controlling the supply of fuel to said burner, a vessel positioned to be affected by the condition of said burner, a substance in said vessel adapted to condense and vaporize in response to changes in the condition of said burner,.and an electrical circuit including said motor and said substance whereby said fluid circulator and said burner are co-ordinately controlled by the condition of said burner.

23. In combination a three-fluid absorption refrigerating system including a motor driven inert gas circulator and a refrigerant generator operable by heat, a fuel burner for heating said generator means forsupply fuel to said burner,

means operated by said motor for controlling the supply of fuel to said burner, means providing a pilot flame in igniting relationship to said burner,

and means including an electric circuit includinga v'aporizable element therein for controlling said motor, the arrangement being such that condensation of said vaporizable element energizes said motor to operate said fuel supply control mechanism to open position.

24. Control mechanism comprising a fuel burner, a valve for controlling the supply of fuel to said burner, an electrical control circuit including a valve actuator, a temperature-responsive regulator and a cut-off device, said cut-off device comprising an element positioned adjacent said burner to be affected by the heat thereof and adapted to change phase when the flame is extinguished to close an electrical circuit operative when energized to de-energize said valve actuator to discontinue the supply of fuel to said burner.

25. Control mechanism for a fuel burner comprising an electrical circuit including means for governing the supply of fuel to said burner and a flame failure cutoff comprising an element adapted to change phase and electrical conductivity in response to failure of flame on said burner whereby said governing means discontinues the supply of fuel to said burner, said cutoff including a wall portion to be subjected to the burner flame which is heat conductive.

26. In combination a gas burner, an electric motor, said motor having a field piece provided with an opening therethrough, a magnetic valve element in said opening, and means including said opening and said magnetic valve element for supplying gas to said burner.

27. A flame responsive control device comprising an electrical circuit including a casing element to be subjected to a flame constructed of material which is heat conductive and electrically conductive, a material within said casing which changes phase in response to changes in the thermal condition thereof and which is electrically conducting in one phase and electrically non-conducting in another phase, means providing for a first electrical connection for said circuit to said casing anda second electrical connection to said material, and means providing an insulated seal for said second connection through the wall of said casing whereby said circuit is open or closed in accordance with the phase of said material.

28. In combination with a burner and a fuel supply means therefor, a safety control mechanism for said burner comprising a safety control said circuit is eiiergized .todiscontinue the supply of fuel to said bfumerjby said fuel supplimeaus and a flame resiio sive device positioned to be heated by and arranged to maintain said circuit open when heated and to close said circuit in response to failure of flame at said v 2,274; electric circuitiii'cludingimeansarranged when see "'7 burner, saiddevice comprising an electrically conductive casing forming a part of said .control circuit, and a vaporizable material in said casing and :included in said electric circuit which is non-conductive when vaporized by the heat of I 7 said burner." I r CHARLES H. MecFAItI-AND. 

